A woman who has put on a few pounds since the last time that a random 72 year old Uncle will say to Larry, the cousin twice removed, this kind of thing:
Uncle: "Golly! That's Suzanne? She has gotten to be a real Plump Sister since the last time I saw her."
Larry: "Must've been back in the Seventies. Before the kid. Kids. Who knows."
Uncle: "It was May 1979. When they got married...wow she just blimped out!" Larry: "Total butterball. Plump Sister, shame."
1. Used to describe someone who is (slightly) chubby, and as become so over the christmas/summer holiday period.
2. Or, someone who morbidly obese and you don't want to hurt their feelings, yet you stil want to bring them to the attention of their weight gain.
1. 'oh mighty me darling, you seemed to have gained ten pounds over the christmas period! Time for the old detox!'
2. 'S**t! Look at that big moma, shes ever bigger than yours!'
'Mate, shut it, be nice to her, shes my aunt'